Why is it that I can hear "Big Sis" used on Greek and not bat an eyelid, but the thought of using it for Marimite makes me cringe? They're the exact same sort of mentorship system, so it's as valid an English equivalent as it would be if they were actual sisters. Yes, it's casual, but it can also be affectionate, and I could see a formal speaker using it if it were a standardized part of the system. Maybe it's that I never actually heard it used that way until Greek (I've never been in a sorority and aren't close to anyone who is), which was only just recently, long after I first saw and read Marimite. Or maybe it just doesn't fit with the atmosphere at Lillian. Thoughts?

From what I know having a sister in a sorority, it isn't quite the same relationship. Big sis[ter](s) is less of a hierarchical system in sororities, and DEFINITELY less formal. It seems to be designed more around keeping the unit together through a web of "family" relations than it is defining an individual 1-1 relationship.I think part of it is that Lilian has an air of exclusivity to the relationships (not just for dramatic purposes) that really makes "sis" sort of a loose translation at best...

In the fictional sorority I'm talking about, while everyone called each other "sister," there were specific Big Sister-Little Sister pairs (with the Little Sisters being the pledges to the sorority). The only girls the pledges called "Big Sis" were their Big Sisters. But it was a much smaller and tighter-knit group of people than the population of Lillian, so it's definitely a bit of a different feel, yeah. Thanks for the insight!